The copy_from_user_mmap_sem function in fs/splice.c in the Linux kernel 2.6.22 through 2.6.24 does not validate a certain userspace pointer before dereference, which allow local users to read from arbitrary kernel memory locations.
isec.pl/vulnerabilities/isec-0026-vmsplice_to_kernel.txt
secunia.com/advisories/28835
secunia.com/advisories/28875
secunia.com/advisories/28896
www.debian.org/security/2008/dsa-1494
www.kernel.org/pub/linux/kernel/v2.6/ChangeLog-2.6.24.1
www.securityfocus.com/archive/1/487982/100/0/threaded
www.securityfocus.com/bid/27704
www.securityfocus.com/bid/27796
www.vupen.com/english/advisories/2008/0487/references
www.exploit-db.com/exploits/5093
www.redhat.com/archives/fedora-package-announce/2008-February/msg00254.html
www.redhat.com/archives/fedora-package-announce/2008-February/msg00255.html